A pouch having a moisture-proof property adapted to accommodate a medicine or the like composed of a compound film material having one layer comprising a resin film with a superior moisture-proof property and gas-barrier property and the other layer comprising a resin film having a good heat adhesive property is known. These layers are laminated with the resin film having the good heat adhesive property being disposed inside when a pouch is formed by utilizing such compound films, and both the layers are thermally bonded or heat fused to each other along the laminated edge portions thereof.
In the pouch of this kind, when a pouch is manufactured by such compound films, since the resin film layer disposed outside having the superior moisture-proof and gas-barrier properties also generally has a heat resisting property and is capable of being easily printed, various advantages may be provided other than the moisture-proof property. On the contrary, a pouch made of such material has a considerably large tear strength, i.e. tear resistance, so that much labour is required to tear the pouch to take out the inner content such as medicine of powder type. For example, it is hard to open the pouch by usual finger force, requiring a scissor or a knife to cut the pouch and take out the inner content.
In order to solve this problem, there has been proposed a pouch in which a slit is formed in one side portion of the outer side resin film of the pouch having a large tear strength to thereby open the pouch using only fingers with a small force.
However, a such pouch having the slit formed in the outside resin film, at the time of manufacturing a compound film by laminating the resin film having the slit on the heat adhesive resin film, may cause the slit to be widely opened when the resin films are laminated, damaging the moisture-proof property. Moreover one end edge of the slit may be overlapped with another end edge forming a staged portion, damaging the opening ability of the pouch. Accordingly, a defective pouch with a poor moisture-proof property may be formed. In an adverse case, it becomes difficult to open the pouch.
Furthermore, in general, the resin film has an orientation along which the resin film is easily torn, and accordingly, even if the slit is formed, an opening line 6, as shown in FIG. 1, is offset from the slit 1 in a direction along which the resin film is easily torn. Therefore, it is difficult to control the tearing direction of the pouch only by the formation of the slit 1. That is, when the pouch is formed, it is necessary to consider the orientation of the resin film to be used.
In order to prevent, those instances where the slit is widely opened and where one end edge of the slit is overlapped with another end edge thereof forming a staged portion, there is proposed a countermeasure, such as disclosed in the Japanese Utility Model Publication No. HEI (JP-Y2-HEI) 4-20759, in which a resin film having a slit 1 and very short un-cut portions 2 (FIG. 2) is laminated on another resin film having a good heat adhesive property. A pouch formed of such a compound film material does not have such a slit defect and provides an improved openable property.
However, in such a pouch, there remains a problem because the opening line is likely to be torn in a manner offset from the slit to a direction along the orientation of the resin film material used for the formation of the compound film, and particularly, even in the above improved manner, this tendency is likely caused at the un-cut portions of the slit, thus also providing a significant problem even in this improved pouch manufacturing method.